A variety of electronic communications systems, including electronic email (“email”) systems and instant messaging (IM) system are well known. Such communication systems are frequently used for collaboration on documents or other electronic files. In such communication systems documents or other electronic files can typically be added as attachments. However, in such communication systems, the presence of attachments serves merely to provide access to the attachment to users. In order to display, modify or otherwise interact with the attachment, the users must download a local copy of the attachment. Moreover, any display, modification or other interaction with the attachment that is performed by a user is not known to other recipients of the email or other participants in the IM chat. In order to share modifications or interactions with attachment, the user must send the revised attachment to other users. This method of sharing modifications to attachments is inefficient, because it requires substantial user intervention and creates situations where multiple users have modified an attachment, resulting in multiple competing versions of the attachment. These shortfalls of conventional communication systems become increasingly problematic as the number of users collaborating on the attachment increases.